1. Field of the Invention
The present invention relates to an endoscope, and particularly to an endoscope having an insert portion to be inserted into a deep digestive tract, such as small intestine and large intestine, for observation.
2. Description of the Related Art
When an insert portion of an endoscope is inserted into a deep digestive tract, such as small intestine, simply pushing the insert portion, in many cases, will not transfer the force to the tip of the insert portion because of complex bends of the intestinal tract, making deep insertion difficult. For example, when the insert portion is bent or flexed more than necessary, the insert portion cannot be inserted any deeper. To address this problem, there has been proposed a method for preventing the insert portion from being bent or flexed more than necessary by covering the insert portion of the endoscope with an insert assist tool, inserting the insert portion covered by the insert assist tool in a body cavity and using the insert assist tool to guide the insert portion.
Japanese Patent Application Laid-Open No. 2005-230083 describes an endoscope apparatus including a first balloon provided at the tip of an insert portion of the endoscope and a second balloon provided at the tip of an insert assist tool (also referred to as an overtube or a sliding tube). The first and second balloons can be inflated to secure the insert portion and the insert assist tool in the intestinal tract of the small intestine or the like. Therefore, by repeating inflation and deflation of the first and second balloons and alternately inserting the insert portion and the insert assist tool, the insert portion can be inserted deep into the intestinal tract of the small intestine or the like that bends in a complex manner.